3.1. Field of the Invention
This invention relates generally to information security. More particularly, this invention relates to methods and systems for enabling the secure, private display of visual content on various display screens (e.g., computer monitor, television, video player, movie theater, mobile phone, automated teller machine, security screening workstations, tactical displays). Even more particularly, the present invention addresses the problem of displaying data privately and securely by displaying data legibly within the gaze of a reader and illegibly outside of the reader's gaze. The present invention has applications in the fields of computer science, computer security, and digital rights management.
3.2. Description of the Related Art
Computer terminals and other display devices are often vulnerable to surreptitious surveillance by individuals seeking to gain confidential information presented on the display. Even a casual glance at a computer monitor can yield confidential information that should not be disclosed to unauthorized individuals. Such sensitive information includes records that are protected by government regulation (e.g. medical or financial records), proprietary corporate information, classified government information, or personal information. Password security and data encryption programs do not provide any protection against an attacker who simply reads displayed confidential content over an authorized user's shoulder, or who collects electromagnetic or optical emanations from the user's device to reproduce the contents of the user's display.
In public spaces, it is difficult to achieve privacy of information on conventional display systems. On airplanes, in coffee shops, in office environments, at ATM machines, in voting booths, at kiosks, at reception desks in doctor's offices, even on mobile phones, important private information is susceptible to unintentional or intentional disclosure. The privacy systems available today provide only casual protection against information disclosure. Systems such as plastic shields mounted over a display device to direct the emitted signal within a narrowed range of view are similarly limited. Moreover, there is no guarantee that the user will use these systems properly or at all.
Other systems for providing security from eavesdroppers have employed gazetrackers, to attempt to protect the exchange of data from the authorized user to the system. More particularly, such prior art systems provide mechanisms that enable a user to securely enter information into a computer using the gazepoint to simulate a traditional computer cursor. For example, U.S. Pat. No. 6,282,553, to Flickner et al., describes a system that enables a user to communicate a password to an ATM machine by indicating the characters to be selected through use of gazepoint tracking, supplemented with a single selection key. However, none of these prior art systems can display information securely from the system to an authorized user.
In certain situations, where data is of particularly high value, or where an attacker is highly motivated to acquire data, some users, such as governments and financial institutions, implement protections against compromising emissions security (“EMSEC”), such as developed by the National Security Agency's so-called “TEMPEST” program. Such “TEMPEST” protection systems are concerned with blocking release of information-bearing signals that can emanate from computer systems as sound, light, vibration, electro-magnetic waves, and other signal patterns. Nevertheless, conventional solutions to EMSEC threats still do not directly address the risk of visual eavesdropping on computer display contents. Thus, TEMPEST-protected displays remain unprotected from visual eavesdropping threats.
What is needed is a display method that delivers content only to the authorized user's view in a manner that is perceptually equivalent to viewing the full fidelity content, but does not expose the content to any unauthorized viewers. The present invention meets these and other needs.